270 EGGS OF BRITISH BIRDS. 



In this country the bird usually builds under the eaves of houses 

 or some other overhanging ledge. The outside shell of the nest is 

 almost entirely composed of mud. The birds do not build much 

 at a time, but allow one layer to dry before another is placed, so 

 that each nest takes ten days or a fortnight to finish. The mud 

 is brought in little pellets, and a few straws or dry grass, or even 

 hair, are intermixed to bind it together. Sometimes two or three 

 nests are built together ; and in some localities they are placed in 

 rows one under the other. The inside is lined with dry grass and 

 a few feathers. The nest is rounded in form, the quarter of 

 an upright oval, and the hole which admits the birds is at the 

 top, generally in the middle, but often in one corner. The lining 

 materials are chiefly collected as the bird is on the wing — straws 

 and feathers which the wind blows into the air. 



The eggs are from four to six in number. They are pure 

 glossy white, and the shell is very smooth. They vary in length 

 from 0'8 to 0'7 inch, and in breadth from 055 to 0'52 inch, and 

 very closely resemble those of the Sand Martin, but are a trifle 

 larger, somewhat coarser grained, and more polished. 



THE SAND MAKTIN. 



{Hirundo riparia.)* 



Plate 58a, Fig. 18. 



The Sand Martin is found throughout the British Islands, in 

 some districts in immense numbers. In Scandinavia its colonies 

 are found as far north as lat. 70° ; but in the valleys of the 

 Petchora, the Ob, and the Yenisei, the most northerly colonies 

 are in about lat. 67°. Middendorff found it on an island on the 

 Pacific coast of Asia, in lat. 55°, and Dybowsky obtained it in 

 Kamtschatka. In North America it breeds from Bering Straits 

 to Baffin's Bay, up to about lat. 68°. 



Immediately after its arrival in this country the Sand Martin 

 repairs to its breeding place, and the old holes are used as sleeping- 

 places at night. In all cases the bird excavates its own abode, and 

 generally returns to it for several years in succession. Sometimes 

 the holes are perfectly round, at others they will be rectangular, 



* Cotile riparia — Saunders, Manual, p. 159. Clivicola riparia — Sharpe, 

 Handb., I., p. 329. 



